Proteolix Presents Preclinical Data for Oral Proteasome Inhibitor PR-047 at the 50th Annual Meeting of the American Society of Hematology

SOUTH SAN FRANCISCO, Calif., December 08, 2008 /PRNewswire/ -- Proteolix, Inc., today announced results from a series of and studies designed to characterize PR-047, the company's oral proteasome inhibitor. These data were presented today in a poster titled (Abstract # 3671) at the 50th Annual Meeting of the American Society of Hematology (ASH). PR-047 is the first oral compound in a new class of highly specific proteasome inhibitors. Carfilzomib, the lead compound in this class, will be the subject of two oral presentations of Phase 2 data on Tuesday, December 9th. PR-047 was designed by Proteolix scientists to combine the pharmacological properties of carfilzomib with the convenience of oral dosing.

Researchers evaluated PR-047's mechanism, bioavailability and activity in a series of preclinicalstudies. Like carfilzomib, PR-047 was shown to target the chymotrypsin-like activity of the proteasome and induce tumor cell death across multiple human cell lines. Oral administration of PR-047 in rodents and monkeys resulted in rapid and prolonged dose-dependent inhibition of the proteasome. Furthermore, significant proteasome inhibition was achieved at doses well below the maximum-tolerated dose even when administered over five consecutive days, suggesting that repeated daily dosing may be feasible with this molecule. Administration of PR-047 resulted in consistent anti-tumor responses in hematological and solid tumor xenograft models at doses below the maximum-tolerated dose.

"We are pleased by the preclinical data achieved to date with PR-047, which demonstrates a promising combination of proteasome inhibition, anti-tumor activity, bioavailability and tolerability," said Mark Bennett, Ph.D., Vice President of Research at Proteolix. "An effective and tolerable oral proteasome inhibitor would have the potential to provide the clinical benefits of intravenous proteasome inhibitors with added patient convenience and dosing flexibility. With these positive preclinical results in hand, we look forward to advancing PR-047 into clinical trials."

Founded in December 2003, Proteolix, Inc. is a privately-held biopharmaceutical company, headquartered in South San Francisco, dedicated to discovering, developing and commercializing novel therapeutics that target protein degradation pathways for cancer and autoimmune diseases. Proteolix's lead product, carfilzomib, is the first in a new class of highly specific proteasome inhibitors, and is currently in multiple Phase 2 clinical studies to evaluate its safety and efficacy in hematologic and solid tumor malignancies. Proteolix is also developing a pipeline of novel proteasome inhibitors, including an oral proteasome inhibitor (PR-047) and a selective immunoproteasome inhibitor. For additional information on Proteolix, please visit www.proteolix.com.